Serum amyloid A induces G-CSF expression and neutrophilia via Toll-like receptor 2.
The acute-phase protein serum amyloid A (SAA) is commonly considered a marker for inflammatory diseases; however, its precise role in inflammation and infection, which often result in neutrophilia, remains ambiguous. In this study, we demonstrate that SAA is a potent endogenous stimulator of granulocyte colony-stimulated factor (G-CSF), a principal cytokine-regulating granulocytosis. This effect of SAA is dependent on Toll-like receptor 2 (TLR2). Our data demonstrate that, in mouse macrophages, both G-CSF mRNA and protein were significantly increased after SAA stimulation. The induction of G-CSF was blocked by an anti-TLR2 antibody and markedly decreased in the TLR2-deficient macrophages. SAA stimulation results in the activation of nuclear factor-kappaB and binding activity to the CK-1 element of the G-CSF promoter region. In vitro reconstitution experiments also support that TLR2 mediates SAA-induced G-CSF expression. In addition, SAA-induced secretion of G-CSF was sensitive to heat and proteinase K treatment, yet insensitive to polymyxin B treatment, indicating that the induction is a direct effect of SAA. Finally, our in vivo studies confirmed that SAA treatment results in a significant increase in plasma G-CSF and neutrophilia, whereas these responses are ablated in G-CSF- or TLR2-deficient mice.
He
Rong L
RL
Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612, USA.
Zhou
Jian
J
Hanson
Crystal Z
CZ
Chen
Jia
J
Cheng
Ni
N
Ye
Richard D
RD
D000210:Acute-Phase Reaction / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D019286:Endopeptidase K / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020218:Response Elements / Q000502:physiology; D000685:Serum Amyloid A Protein; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D000906:Antibodies; D018836:Inflammation Mediators; D016328:NF-kappa B; D012333:RNA, Messenger; D000685:Serum Amyloid A Protein; C495342:TLR2 protein, human; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D016179:Granulocyte Colony-Stimulating Factor; D019286:Endopeptidase K; D011112:Polymyxin B